Radio frequency module and communication device

ABSTRACT

A radio frequency module includes: a module board that includes a first principal surface and a second principal surface on opposite sides of the module board; a power amplifier; a first circuit component; and a power amplifier (PA) control circuit configured to control the power amplifier. The power amplifier includes: an input terminal; an output terminal; first and second amplifying elements disposed parallel to the input terminal; and an output transformer connected between the output terminal and output terminals of the first and second amplifying elements. The PA control circuit is disposed on the second principal surface, and the first and second amplifying elements are both disposed on the first principal surface.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on and claims priority of Japanese Patent Application No. 2020-043945 filed on Mar. 13, 2020. The entire disclosure of the above-identified application, including the specification, drawings and claims is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a radio frequency module and a communication device.

BACKGROUND

A power amplifier that amplifies radio frequency transmission signals is provided in a mobile communication apparatus such as a mobile phone.

Japanese Unexamined Patent Application Publication No. 2010-118916 discloses a difference amplifying type power amplifier that includes a first transistor to which a non-inverted input signal is input, a second transistor to which an inverted input signal is input, and a transformer disposed on the output terminal side of the first transistor and the second transistor. The transformer includes two magnetically coupled primary coils and one secondary coil. The two primary coils are connected in parallel, and are each magnetically coupled with the secondary coil, so that the input impedance of the primary coils can be decreased without decreasing the Q factor. Accordingly, power gain can be improved.

SUMMARY Technical Problems

However, as recognized by the present inventor, if the difference amplifying type power amplifier disclosed in Japanese Unexamined Patent Application Publication No. 2010-118916 is achieved using a single radio frequency module, many circuit elements are included in the power amplifier, which results in an increase in the size of the radio frequency module.

The present disclosure has been conceived to solve the above-identified and other problems, and provides a small radio frequency module that includes a difference amplifying type power amplifier, and a communication device that includes the radio frequency module.

Solutions

In order to provide such a radio frequency module, a radio frequency module according to an aspect of the present disclosure includes: a module board that includes a first principal surface and a second principal surface on opposite sides of the module board; a power amplifier configured to amplify a transmission signal; a first circuit component; and a control circuit configured to control the power amplifier. The power amplifier includes: a first amplifying element; a second amplifying element; and an output transformer that includes a first coil and a second coil. An end of the first coil is connected to an output terminal of the first amplifying element. Another end of the first coil is connected to an output terminal of the second amplifying element. An end of the second coil is connected to an output terminal of the power amplifier. The control circuit is disposed on the first principal surface, and the first circuit component or both the first amplifying element and the second amplifying element are disposed on the second principal surface.

Advantageous Effects

According to the present disclosure, a small radio frequency module that includes a difference amplifying type power amplifier, and a communication device that includes the radio frequency module are provided.

BRIEF DESCRIPTION OF DRAWINGS

These and other advantages and features will become apparent from the following description thereof taken in conjunction with the accompanying Drawings, by way of non-limiting examples of embodiments disclosed herein.

FIG. 1 illustrates a circuit configuration of a radio frequency module and a communication device according to an embodiment.

FIG. 2 illustrates a circuit configuration of a difference amplifying type power amplifier.

FIG. 3A is a schematic diagram illustrating a planar configuration of a radio frequency module (or RF front-end circuitry) according to Example 1.

FIG. 3B is a schematic diagram illustrating a cross-sectional configuration of the radio frequency module according to Example 1.

FIG. 3C is a schematic diagram illustrating a cross-sectional configuration of a radio frequency module according to Variation 1.

FIG. 3D is a schematic diagram illustrating a cross-sectional configuration of a radio frequency module according to Variation 2.

FIG. 4A is a schematic diagram illustrating a planar configuration of a radio frequency module according to Example 2.

FIG. 4B is a schematic diagram illustrating a cross-sectional configuration of the radio frequency module according to Example 2.

DESCRIPTION OF EMBODIMENTS

The following describes in detail embodiments of the present disclosure. Note that the embodiments described below each show a general or specific example. The numerical values, shapes, materials, elements, and the arrangement and connection of the elements, for instance, described in the following embodiments are examples, and thus are not intended to limit the present disclosure. Among the elements in the following examples and variations, elements not recited in any of the independent claims are described as arbitrary elements. In addition, the sizes of elements and the ratios of the sizes illustrated in the drawings are not necessarily accurate. Throughout the drawings, the same numeral is given to substantially the same element, and redundant description may be omitted or simplified.

In the following, a term that indicates a relation between elements such as “parallel” or “perpendicular”, a term that indicates the shape of an element such as “rectangular”, and a numerical range do not necessarily have only strict meanings, and also cover substantially equivalent ranges that include a difference of about several percent, for example.

In the following, regarding A, B, and C mounted on a board, “C is disposed between A and B in a plan view of a board (or a principal surface of a board)” means at least one of line segments that connect arbitrary points in A and B passes through a region of C in a plan view of a board. A plan view of a board means that a board and a circuit element mounted on the board are viewed, being orthogonally projected onto a plane parallel to a principal surface of the board. In addition, “on” in expressions such as mounted on, disposed on, provided on, and formed on, for example, does not necessarily indicate direct contact.

In the following, a “transmission path” means a transfer route that includes, for instance, a line through which a radio frequency transmission signal propagates, an electrode directly connected to the line, and a terminal directly connected to the line or the electrode. Further, a “reception path” means a transfer route that includes, for instance, a line through which a radio frequency reception signal propagates, an electrode directly connected to the line, and a terminal directly connected to the line or the electrode. In addition, a “transmission and reception path” means a transfer route that includes, for instance, a line through which a radio frequency transmission signal and a radio frequency reception signal propagate, an electrode directly connected to the line, and a terminal directly connected to the line or the electrode.

In the following, “A and B are connected” applies not only when A and B are physically connected, but also when A and B are electrically connected.

Embodiment

[1. Circuit Configuration of Radio Frequency Module 1 and Communication Device 5]

FIG. 1 illustrates a circuit configuration of radio frequency module 1 and communication device 5 according to an embodiment.

As illustrated in FIG. 1, communication device 5 includes radio frequency module 1, antenna 2, radio frequency (RF) signal processing circuit (RF integrated circuit (RFIC)) 3, and baseband signal processing circuit (BB integrated circuit (BBIC)) 4.

RFIC 3 is an RF signal processing circuit that processes radio frequency signals transmitted and received by antenna 2. Specifically, RFIC 3 processes a reception signal input through a reception path of radio frequency module 1 by down-conversion, for instance, and outputs a reception signal generated by being processed to BBIC 4. RFIC 3 processes a transmission signal input from BBIC 4 by up-conversion, for instance, and outputs a transmission signal generated by being processed to a transmission path of radio frequency module 1.

BBIC 4 is a circuit that processes signals using an intermediate frequency band lower than the frequency range of a radio frequency signal transferred in radio frequency module 1. A signal processed by BBIC 4 is used, for example, as an image signal for image display or as an audio signal for talk through a loudspeaker.

RFIC 3 also functions as a controller that controls connection made by switches 51, 52, and 53 included in radio frequency module 1, based on a communication band (a frequency band) to be used. Specifically, RFIC 3 changes connection made by switches 51 to 53 included in radio frequency module 1 according to control signals (not illustrated). Specifically, RFIC 3 outputs digital control signals for controlling switches 51 to 53 to power amplifier (PA) control circuit 80. PA control circuit 80 of radio frequency module 1 controls connection and disconnection of switches 51 to 53 by outputting digital control signals to switches 51 to 53 according to the digital control signals input from RFIC 3.

RFIC 3 also functions as a controller that controls the gain of power amplifier 10 included in radio frequency module 1 and power supply voltage Vcc and bias voltage Vbias that are supplied to power amplifier 10. Specifically, RFIC 3 outputs digital control signals to control signal terminal 130 of radio frequency module 1. PA control circuit 80 of radio frequency module 1 adjusts the gain of power amplifier 10 by outputting a control signal, power supply voltage Vcc, or bias voltage Vbias to power amplifier 10 according to a digital control signal input through control signal terminal 130. Note that a control signal terminal that receives, from RFIC 3, a digital control signal for controlling the gain of power amplifier 10 and a control signal terminal that receives, from RFIC 3, digital control signals for controlling power supply voltage Vcc and bias voltage Vbias that are supplied to power amplifier 10 may be different terminals. The controller may be disposed outside of RFIC 3, and may be disposed in BBIC 4, for example.

Antenna 2 is connected to antenna connection terminal 100 of radio frequency module 1, radiates a radio frequency signal output from radio frequency module 1, and receives and outputs a radio frequency signal from the outside to radio frequency module 1.

Note that antenna 2 and BBIC 4 are not necessarily included in communication device 5 according to the present embodiment.

Next, a detailed configuration of radio frequency module 1 is to be described.

As illustrated in FIG. 1, radio frequency module 1 includes antenna connection terminal 100, power amplifier 10, low noise amplifier 20, transmission filters 30T and 40T, reception filters 30R and 40R, PA control circuit 80, matching circuits 61, 62, and 63, switches 51, 52, and 53, and diplexer 35.

Antenna connection terminal 100 is an example of an input/output terminal, and is an antenna common terminal connected to antenna 2.

Power amplifier 10 is a difference amplifying type amplifier circuit that amplifies radio frequency signals in communication band A and communication band B input through transmission input terminal 110.

PA control circuit 80 adjusts the gain of power amplifier 10 according to, for instance, a digital control signal input through control signal terminal 130. PA control circuit 80 may be formed as a semiconductor integrated circuit (IC). A semiconductor IC includes a complementary metal oxide semiconductor (CMOS), for example, and specifically, formed by a silicon on insulator (SOI) process. Accordingly, such a semiconductor IC can be manufactured at a low cost. Note that the semiconductor IC may include at least one of gallium arsenide (GaAs), silicon germanium (SiGe), or gallium nitride (GaN). Thus, a radio frequency signal having high amplification quality and high noise quality can be output.

Low noise amplifier 20 amplifies radio frequency signals in communication bands A and B while noise is kept low, and outputs the amplified radio frequency signals to reception output terminal 120.

Transmission filter 30T is disposed on transmission path AT that connects power amplifier 10 and antenna connection terminal 100, and passes a transmission signal in the transmission band of communication band A, within a transmission signal amplified by power amplifier 10. Transmission filter 40T is disposed on transmission path BT that connects power amplifier 10 and antenna connection terminal 100, and passes a transmission signal in the transmission band of communication band B, within a transmission signal amplified by power amplifier 10.

Reception filter 30R is disposed on reception path AR that connects low noise amplifier 20 and antenna connection terminal 100, and passes a reception signal in the reception band of communication band A, within a reception signal input through antenna connection terminal 100. Reception filter 40R is disposed on reception path BR that connects low noise amplifier 20 and antenna connection terminal 100, and passes a reception signal in the reception band of communication band B, within a reception signal input through antenna connection terminal 100.

Transmission filter 30T and reception filter 30R are included in duplexer 30 having a passband that is communication band A. Duplexer 30 transfers a transmission signal and a reception signal in communication band A by frequency division duplex (FDD). Transmission filter 40T and reception filter 40R are included in duplexer 40 having a passband that is communication band B. Duplexer 40 transfers a transmission signal and a reception signal in communication band B by FDD.

Note that duplexers 30 and 40 may each be a multiplexer that includes only a plurality of transmission filters, a multiplexer that includes only a plurality of reception filters, or a multiplexer that includes a plurality of duplexers. Transmission filter 30T and reception filter 30R may not be included in duplexer 30, and may be a single filter for signals transferred by time division duplex (TDD). In this case, one or more switches that switch between transmission and reception are disposed upstream, disposed downstream, or disposed upstream and downstream from transmission filter 30T and reception filter 30R.

Matching circuit 61 is disposed on a path that connects switch 53 and duplexer 30, and matches the impedance between (i) duplexer 30 and (ii) diplexer 35 and switch 53. Matching circuit 62 is disposed on a path that connects switch 53 and duplexer 40, and matches the impedance between (i) duplexer 40 and (ii) diplexer 35 and switch 53.

Matching circuit 63 is disposed on reception paths that connect low noise amplifier 20 and reception filters 30R and 40R, and matches the impedance between (i) low noise amplifier 20 and (ii) reception filters 30R and 40R.

Note that a matching circuit that matches the impedance between (i) power amplifier 10 and (ii) transmission filters 30T and 40T may be disposed on transmission paths that connect power amplifier 10 and transmission filters 30T and 40T.

Switch 51 includes a common terminal and two selection terminals. The common terminal of switch 51 is connected to output terminal 116 of power amplifier 10. One of the selection terminals of switch 51 is connected to transmission filter 30T, and the other selection terminal of switch 51 is connected to transmission filter 40T. This connection configuration allows switch 51 to switch connection of power amplifier 10 between transmission filter 30T and transmission filter 40T. Switch 51 includes a single pole double throw (SPDT) switch circuit, for example.

Switch 52 includes a common terminal and two selection terminals. The common terminal of switch 52 is connected to the input terminal of low noise amplifier 20 via matching circuit 63. One of the selection terminals of switch 52 is connected to reception filter 30R, and the other selection terminal of switch 52 is connected to reception filter 40R. This connection configuration allows switch 52 to switch between connection and disconnection of low noise amplifier to/from reception filter 30R and between connection and disconnection of low noise amplifier 20 to/from reception filter 40R. Switch 52 includes an SPDT switch circuit, for example.

Switch 53 is an example of an antenna switch and is connected to antenna connection terminal 100 via diplexer 35, and switches connection of antenna connection terminal 100 between (1) transmission path AT and reception path AR and (2) transmission path BT and reception path BR. Note that switch 53 includes a multiple connection switch circuit that allows simultaneous connections of (1) and (2) above.

Diplexer 35 is an example of a multiplexer, and includes filters 35L and 35H. Filter 35L has a passband that is a frequency range including communication bands A and B, and filter 35H has a passband that is a different frequency range other than the frequency range including communication bands A and B. One terminal of filter 35L and one terminal of filter 35H are connected in common to antenna connection terminal 100. Filters 35L and 35H are each an LC filter that includes at least one of a chip inductor or a chip capacitor, for example. Note that when the frequency range including communication bands A and B is lower than the above different frequency range, filter 35L may be a low pass filter, and filter 35H may be a high pass filter.

Note that transmission filters 30T and 40T and reception filters 30R and 40R described above may each be one of, for example, an acoustic wave filter that uses surface acoustic waves (SAWs), an acoustic wave filter that uses bulk acoustic waves (BAWs), an inductor-capacitor (LC) resonance filter, and a dielectric filter, and furthermore, are not limited to those filters.

Matching circuits 61 to 63 are not necessarily included in the radio frequency module according to the present disclosure.

In the configuration of radio frequency module 1, power amplifier 10, switch 51, transmission filter 30T, matching circuit 61, switch 53, and filter 35L are included in a first transmission circuit that transfers transmission signals in communication band A toward antenna connection terminal 100. Filter 35L, switch 53, matching circuit 61, reception filter 30R, switch 52, matching circuit 63, and low noise amplifier 20 are included in a first reception circuit that transfers reception signals in communication band A from antenna 2 through antenna connection terminal 100.

Power amplifier 10, switch 51, transmission filter 40T, matching circuit 62, switch 53, and filter 35L are included in a second transmission circuit that transfers transmission signals in communication band B toward antenna connection terminal 100. Filter 35L, switch 53, matching circuit 62, reception filter 40R, switch 52, matching circuit 63, and low noise amplifier 20 are included in a second reception circuit that transfers reception signals in communication band B from antenna 2 through antenna connection terminal 100.

According to the above circuit configuration, radio frequency module 1 can carry out at least one of transmission, reception, or transmission and reception of a radio frequency signal in communication band A or B. Furthermore, radio frequency module 1 can carry out at least one of simultaneous transmission, simultaneous reception, or simultaneous transmission and reception of radio frequency signals in communication bands A and B.

Note that in the radio frequency module according to the present disclosure, the two transmission circuits and the two reception circuits may not be connected to antenna connection terminal 100 via switch 53, and may be connected to antenna 2 via different terminals. It is sufficient if the radio frequency module according to the present disclosure includes at least one of the first transmission circuit or the second transmission circuit.

In the radio frequency module according to the present disclosure, it is sufficient if the first transmission circuit includes power amplifier 10 and at least one element out of transmission filter 30T, switches 51 and 53, and matching circuit 61. It is sufficient if the second transmission circuit includes power amplifier 10 and at least one element out of transmission filter 40T, switches 51 and 53, and matching circuit 62.

Low noise amplifier 20 and switches 51 to 53 may be formed in a single semiconductor IC. The semiconductor IC includes a CMOS, for example, and is specifically formed by the SOI process. Accordingly, such a semiconductor IC can be manufactured at a low cost. Note that the semiconductor IC may include at least one of GaAs, SiGe, or GaN. Thus, a radio frequency signal having high amplification quality and high noise quality can be output.

Here, a circuit configuration of power amplifier 10 is to be described in detail.

FIG. 2 illustrates a circuit configuration of power amplifier 10. As illustrated in FIG. 2, power amplifier 10 includes input terminal 115, output terminal 116, amplifying element 12 (a first amplifying element), amplifying element 13 (a second amplifying element), amplifying element 11, interstage transformer (transformer) 14, capacitor 16, and output transformer (unbalance-balance transforming element) 15.

The input terminal of amplifying element 11 is connected to input terminal 115, and the output terminal of amplifying element 11 is connected to an unbalance terminal of interstage transformer 14. One balance terminal of interstage transformer 14 is connected to the input terminal of amplifying element 12, and the other balance terminal of interstage transformer 14 is connected to the input terminal of amplifying element 13.

A radio frequency signal input through input terminal 115 is amplified by amplifying element 11 in a state in which bias voltage Vcc1 is applied to amplifying element 11. Interstage transformer 14 applies an unbalance-balance transform (i.e., a transformation of an unbalanced line to a balanced line that carries non-inverted and inverted versions of the signal) to the amplified radio frequency signal. At this time, a non-inverted input signal is output through the one balance terminal of interstage transformer 14, and an inverted input signal is output through the other balance terminal of interstage transformer 14.

Output transformer 15 includes primary coil (first coil) 15 a and secondary coil (second coil) 15 b. One end of primary coil 15 a is connected to the output terminal of amplifying element 12, and the other end of primary coil 15 a is connected to the output terminal of amplifying element 13. Bias voltage Vcc2 is supplied to a middle point of primary coil 15 a. One end of secondary coil 15 b is connected to output terminal 116, and the other end of secondary coil 15 b is connected to the ground. Stated differently, output transformer 15 is connected between (i) output terminal 116 and (ii) the output terminal of amplifying element 12 and the output terminal of amplifying element 13.

Capacitor 16 is connected between the output terminal of amplifying element 12 and the output terminal of amplifying element 13.

Respective impedances of lines that carry a non-inverted input signal amplified by amplifying element 12 and an inverted input signal amplified by amplifying element 13 are transformed by output transformer 15 and capacitor 16, while the signals are maintained in antiphase (or antipodal phase relationship) with each other. Specifically, output transformer 15 and capacitor 16 match the output impedance of power amplifier 10 at output terminal 116 to input impedance of switch 51 and transmission filters 30T and 40T illustrated in FIG. 1. Note that a capacitive element connected between the ground and a path that connects output terminal 116 and secondary coil 15 b contributes to the impedance matching. Further note that the capacitive element may be disposed in series on the path that connects output terminal 116 and secondary coil 15 b, or may not be included.

Here, amplifying elements 11 to 13, interstage transformer 14, and capacitor 16 constitute differential amplifier circuit 10A. In particular, amplifying elements 11 to 13 and interstage transformer 14 are integrally formed in various configurations such as being formed in a single chip or respectively mounted on a same substrate, for instance. In contrast, output transformer 15 needs to have a high Q factor to handle a high-power transmission signal, and thus is not formed integrally with amplifying elements 11 to 13 or interstage transformer 14, for instance. Stated differently, among circuit components included in power amplifier 10, circuit components except the output transformer 15 constitute the differential amplifier circuit 10A.

Note that amplifying element 11 and capacitor 16 optionally need not be included in differential amplifier circuit 10A.

According to the circuit configuration of power amplifier 10, amplifying elements 12 and 13 operate in antiphase relationship with respect to each other. At this time, fundamental-wave currents flow through amplifying elements 12 and 13 in antiphase with each other, that is, in opposite directions, and thus fundamental-wave currents do not flow into a ground line or a power supply line disposed at a substantially equal distance from amplifying elements 12 and 13. Accordingly, inflow of unnecessary (or undesired) currents to the above lines can be avoided, and thus decrease in power gain that is experienced in a conventional power amplifier can be reduced. Further, a non-inverted signal and an inverted signal amplified by amplifying elements 12 and 13 are combined, and thus noise components superimposed similarly on the signals can be cancelled out, and unnecessary waves such as harmonic components, for example, can be suppressed.

Note that amplifying element 11 is not necessarily included in power amplifier 10. An element that transforms an unbalanced input signal into a non-inverted input signal and an inverted input signal is not limited to interstage transformer 14. Capacitor 16 is optional for impedance matching.

Amplifying elements 11 to 13 and low noise amplifier 20 each include a field effect transistor (FET) or a hetero-bipolar transistor (HBT) made of a silicon-based CMOS or GaAs, for example.

Here, when radio frequency module 1 is mounted on a single mounting board, many circuit elements (amplifying elements 11 to 13, interstage transformer 14, output transformer 15, and capacitor 16) are included in power amplifier 10, which results in an increase in the size of radio frequency module 1. If the elements are mounted highly densely, a high-power transmission signal output from power amplifier 10 and a control signal output from PA control circuit 80 interfere with circuit components included in radio frequency module 1, and the quality of a radio frequency signal output from radio frequency module 1 deteriorates, which is a problem.

To address this, radio frequency module 1 according to the present embodiment has a configuration of miniaturizing radio frequency module 1 while reducing deterioration of the quality of a radio frequency signal output from radio frequency module 1. The following describes the configuration of radio frequency module 1 that reduces deterioration of the signal quality and also the size thereof.

[2. Arrangement of Circuit Elements of Radio Frequency Module 1A According to Example 1]

FIG. 3A is a schematic diagram illustrating a planar configuration of radio frequency module 1A according to Example 1. FIG. 3B is a schematic diagram illustrating a cross-sectional configuration of radio frequency module 1A according to Example 1, and specifically, illustrates a cross section taken along line IIIB to IIIB in FIG. 3A. Note that (a) of FIG. 3A illustrates a layout of circuit elements when principal surface 91 a out of principal surfaces 91 a and 91 b on opposite sides of module board 91 is viewed from the positive z-axis. On the other hand, (b) of FIG. 3A is a perspective view of a layout of circuit elements when principal surface 91 b is viewed from the positive z-axis. FIG. 3A illustrates output transformer 15 disposed inside of module board 91 with dashed lines.

Radio frequency module 1A according to Example 1 shows a specific arrangement of circuit elements included in radio frequency module 1 according to the embodiment.

As illustrated in FIGS. 3A and 3B, radio frequency module 1A according to this example further includes module board 91, resin members 92 and 93, and external-connection terminals 150, in addition to the circuit configuration illustrated in FIG. 1.

Module board 91 is a board which includes principal surface 91 a (a second principal surface) and principal surface 91 b (a first principal surface) on opposite sides of module board 91, and on which the above transmission circuits and the above reception circuits are mounted. As module board 91, one of a low temperature co-fired ceramics (LTCC) board, a high temperature co-fired ceramics (HTCC) board, a component-embedded board, a board that includes a redistribution layer (RDL), and a printed circuit board, each having a stacked structure of a plurality of dielectric layers, is used, for example.

Resin member 92 is provided on principal surface 91 a of module board 91, covers at least partially the transmission circuits, at least partially the reception circuits, and principal surface 91 a of module board 91, and has a function of ensuring reliability of mechanical strength and moisture resistance, for instance, of the circuit elements included in the transmission circuits and the reception circuits. Resin member 93 is provided on principal surface 91 b of module board 91, covers at least partially the transmission circuits, at least partially the reception circuits, and principal surface 91 b of module board 91, and has a function of ensuring reliability of mechanical strength and moisture resistance, for instance, of the circuit elements included in the transmission circuits and the reception circuits. Note that resin members 92 and 93 are not necessarily included in the radio frequency module according to the present disclosure.

As illustrated in FIGS. 3A and 3B, in radio frequency module 1A according to this example, differential amplifier circuit 10A, duplexers 30 and 40, matching circuits 61, 62, and 63, and switch 53 are mounted on principal surface 91 a (the second principal surface) of module board 91. On the other hand, PA control circuit 80, low noise amplifier 20, switches 51 and 52, and diplexer 35 are mounted on principal surface 91 b (the first principal surface) of module board 91. Output transformer 15 is disposed inside of module board 91.

In this example, amplifying elements 12 and 13 are mounted on principal surface 91 a (the second principal surface). On the other hand, PA control circuit 80 is mounted on principal surface 91 b (the first principal surface). Further, low noise amplifier 20 is a first circuit component, and is mounted on principal surface 91 b (the first principal surface).

Note that duplexers 30 and 40, switch 53, and matching circuits 61, 62, and 63 are mounted on principal surface 91 a (the second principal surface), but may be mounted on principal surface 91 b (the first principal surface). Switches 51 and 52 and diplexer 35 are mounted on principal surface 91 b (the first principal surface), but may be mounted on principal surface 91 a (the second principal surface).

Power amplifier 10 includes at least amplifying elements 12 and 13, interstage transformer 14, and output transformer 15, and thus includes many circuit elements, which leads to an increase in a mounting area. Consequently, the size of the radio frequency module is likely to increase.

To address this, the above configuration of radio frequency module 1A according to this example allows PA control circuit 80 that controls power amplifier 10 and differential amplifier circuit 10A to be mounted on the two sides, and thus radio frequency module 1 can be miniaturized.

PA control circuit 80 that receives and outputs digital control signals and differential amplifier circuit 10A are disposed with module board 91 being located therebetween, and thus differential amplifier circuit 10A can be prevented from receiving digital noise. Accordingly, deterioration of the quality of a radio frequency signal output from power amplifier 10 can be reduced.

Note that desirably, module board 91 has a multilayer structure in which a plurality of dielectric layers are stacked, and a ground electrode pattern is formed on at least one of the dielectric layers. Accordingly, the electromagnetic field shielding function of module board 91 improves.

In radio frequency module 1A according to this example, a plurality of external-connection terminals 150 are disposed on principal surface 91 b (the first principal surface) of module board 91. Radio frequency module 1A exchanges electrical signals with a motherboard disposed on the negative z-axis side of radio frequency module 1A, via external-connection terminals 150. As illustrated in (b) of FIG. 3A, the external-connection terminals include antenna connection terminal 100, transmission input terminal 110, and reception output terminal 120. Potential of some of external-connection terminals 150 are set to the ground potential of the motherboard. On principal surface 91 b facing the motherboard out of principal surfaces 91 a and 91 b, differential amplifier circuit 10A whose height is not readily decreased is not disposed, and low noise amplifier 20 whose height is readily decreased is disposed, and thus the height of radio frequency module 1A as a whole can be decreased. Further, external-connection terminals 150 used as ground electrodes are disposed around low noise amplifier 20 that greatly affects reception sensitivity of the reception circuits, and thus deterioration of reception sensitivity of the reception circuits can be reduced.

Note that as illustrated in (b) of FIG. 3A and FIG. 3B, external-connection terminals 150 having the ground potential out of external-connection terminals 150 are desirably disposed between PA control circuit 80 and low noise amplifier 20, in a plan view of module board 91.

Accordingly, external-connection terminals 150 used as ground electrodes are disposed between low noise amplifier 20 and PA control circuit 80, and thus deterioration of reception sensitivity can be further reduced.

In this example, matching circuit 63 includes at least an inductor, and the inductor is disposed on principal surface 91 a (the second principal surface).

Accordingly, the inductor and PA control circuit 80 that greatly affect reception sensitivity of the reception circuits are disposed with module board 91 being located therebetween, and thus a digital control line connected to PA control circuit 80 and the inductor can be prevented from being coupled via an electromagnetic field. Accordingly, deterioration of reception sensitivity caused by digital noise can be reduced.

Differential amplifier circuit 10A is a component that generates a great amount of heat, out of circuit components included in radio frequency module 1A. In order to improve heat dissipation of radio frequency module 1A, it is important to dissipate heat generated by differential amplifier circuit 10A to the motherboard through heat dissipation paths having low heat resistance. If differential amplifier circuit 10A is mounted on principal surface 91 b, an electrode line connected to differential amplifier circuit 10A is disposed on principal surface 91 b. Accordingly, the heat dissipation paths include a heat dissipation path along only a planar line pattern (in the xy plane direction) on principal surface 91 b. The planar line pattern is formed of a thin metal film, and thus has high heat resistance. Accordingly, if differential amplifier circuit 10A is disposed on principal surface 91 b, heat dissipation deteriorates.

To address this, radio frequency module 1A according to this example further includes heat-dissipating via-conductor 95V that is connected to a ground electrode of differential amplifier circuit 10A on principal surface 91 a, and extends from principal surface 91 a to principal surface 91 b, as illustrated in FIG. 3B. Heat-dissipating via conductor 95V is connected, on principal surface 91 b, to external-connection terminals 150 having the ground potential out of external-connection terminals 150.

According to this configuration, when differential amplifier circuit 10A is mounted on principal surface 91 a, differential amplifier circuit 10A and external-connection terminals 150 can be connected through heat-dissipating via conductor 95V. Accordingly, as heat dissipation paths for differential amplifier circuit 10A, a heat dissipation path extending along only a planar line pattern in the xy plane direction and having high heat resistance can be excluded from lines on and in module board 91. Thus, miniaturized radio frequency module 1A having improved heat dissipation from differential amplifier circuit 10A to the motherboard can be provided.

Note that in radio frequency module 1A according to this example, low noise amplifier 20 and switches 51 and 52 may be included in single semiconductor IC 70. Accordingly, radio frequency module 1A can be miniaturized.

In radio frequency module 1A according to this example, output transformer 15 is disposed inside of module board 91, but may be mounted on principal surface 91 a or 91 b as a chip circuit component.

Note that desirably, no circuit component is disposed in a region that overlaps a formation region in which output transformer 15 is formed, in a plan view of module board 91. Output transformer 15 needs have a high Q factor to handle a high-power transmission signal, and thus a magnetic field formed by output transformer 15 is desirably not changed by another circuit component being adjacent thereto. Since a circuit component is not formed in the above region, the Q factor of the inductor included in output transformer 15 can be maintained high.

Furthermore, desirably, in a plan view of module board 91, a grand electrode layer is not formed in a region included in module board 91 and overlapping the formation region in which output transformer 15 is formed. According to this configuration, it can be ensured that output transformer 15 and a ground electrode are widely spaced apart from each other, and thus the Q factor of the inductor included in output transformer 15 can be maintained high.

Note that the formation region in which output transformer 15 is formed is defined as follows. The formation region in which output transformer 15 is formed is a minimum region that includes a formation region in which primary coil 15 a is formed and a formation region in which secondary coil 15 b is formed, in a plan view of module board 91.

Here, secondary coil 15 b is defined as a line conductor disposed along primary coil 15 a, in a section in which a first distance from primary coil 15 a is substantially constant. At this time, portions of the line conductor located on both sides of the above section are spaced apart from primary coil 15 a by a second distance longer than the first distance, and one end and the other end of secondary coil 15 b are points at which a distance from the line conductor to primary coil 15 a changes from the first distance to the second distance. Primary coil 15 a is defined as a line conductor disposed along secondary coil 15 b, in a section in which the first distance from secondary coil 15 b is substantially constant. At this time, portions of the line conductor located on both sides of the above section are spaced apart from secondary coil 15 b by the second distance longer than the first distance, and one end and the other end of primary coil 15 a are points at which a distance from the line conductor to secondary coil 15 b changes from the first distance to the second distance.

Alternatively, secondary coil 15 b is defined as a line conductor disposed along primary coil 15 a, in a first section in which the line width is a substantially constant first width. Primary coil 15 a is defined as a line conductor disposed along secondary coil 15 b, in the first section in which the line width is the substantially constant first width.

Alternatively, secondary coil 15 b is defined as a line conductor disposed along primary coil 15 a, in a first section in which the thickness is a substantially constant first thickness. Primary coil 15 a is defined as a line conductor disposed along secondary coil 15 b, in the first section in which the thickness is the substantially constant first thickness.

Alternatively, secondary coil 15 b is defined as a line conductor disposed along primary coil 15 a, in a first section in which a degree of coupling with primary coil 15 a is a substantially constant first degree of coupling. Further, primary coil 15 a is defined as a line conductor disposed along secondary coil 15 b, in the first section in which a degree of coupling with secondary coil 15 b is the substantially constant first degree of coupling.

Note that radio frequency module 1A according to Example 1 may include a transmission matching circuit that is connected to the output terminal of power amplifier 10, and matches impedance between (i) power amplifier 10 and (ii) transmission filters 30T and 40T. The transmission matching circuit may be an integrated passive device (IPD) in which passive elements such as an inductor and a capacitor are mounted on the surface or inside of a silicon (Si) substrate, for example. If the above transmission matching circuit is an IPD, the IPD may be stacked on PA control circuit 80 disposed on principal surface 91 b. According to this configuration, PA control circuit 80 and the IPD for transmission matching are stacked on principal surface 91 b, and thus an increase in the size of radio frequency module 1A can be reduced.

Note that in radio frequency module 1A according to this example, differential amplifier circuit 10A is disposed on principal surface 91 a (the second principal surface), and PA control circuit 80 is disposed on principal surface 91 b (the first principal surface), yet differential amplifier circuit 10A may be disposed on principal surface 91 b (the first principal surface), and PA control circuit 80 may be disposed on principal surface 91 a (the second principal surface).

FIG. 3C is a schematic diagram illustrating a cross-sectional configuration of radio frequency module 1B according to Variation 1. Radio frequency module 1B according to this variation differs from radio frequency module 1A according to Example 1 in that the principal surfaces on which differential amplifier circuit 10A and PA control circuit 80 are disposed are opposite. Note that the location of circuit components other than differential amplifier circuit 10A and PA control circuit 80 is the same as that of radio frequency module 1A according to Example 1.

Specifically, in radio frequency module 1B according to this variation, external-connection terminals 150 are disposed on principal surface 91 b (the first principal surface) of module board 91, differential amplifier circuit 10A is disposed on principal surface 91 b (the first principal surface), and PA control circuit 80 is disposed on principal surface 91 a (the second principal surface).

According to the above configuration of radio frequency module 1B according to this variation, PA control circuit 80 that controls power amplifier 10 and differential amplifier circuit 10A are mounted on the two sides, and thus radio frequency module 1 can be miniaturized. Further, PA control circuit 80 that receives and outputs digital control signals and differential amplifier circuit 10A are disposed with module board 91 being located therebetween, and thus differential amplifier circuit 10A can be prevented from receiving digital noise. Accordingly, deterioration of the quality of a radio frequency signal output from power amplifier 10 can be reduced.

Note that external-connection terminals 150 may be columnar electrodes passing through resin member 93 in the z-axis direction as illustrated in FIGS. 3A, 3B, and 3C, or may be bump electrodes 160 formed on principal surface 91 b as in radio frequency module 1C according to Variation 2 illustrated in FIG. 3D. In this case, resin member 93 may not be provided on principal surface 91 b.

In radio frequency module 1A according to Example 1 and radio frequency module 1B according to Variation 1, external-connection terminals 150 may be disposed on principal surface 91 a. In radio frequency module 1C according to Variation 2, bump electrodes 160 may be disposed on principal surface 91 a.

[3. Arrangement of Circuit Elements of Radio Frequency Module 1D According to Example 2]

FIG. 4A is a schematic diagram illustrating a planar configuration of radio frequency module 1D according to Example 2. FIG. 4B is a schematic diagram illustrating a cross-sectional configuration of radio frequency module 1D according to Example 2 and specifically, illustrates a cross section taken along line IVB to IVB in FIG. 4A. Note that (a) of FIG. 4A illustrates a layout of circuit elements when principal surface 91 a out of principal surfaces 91 a and 91 b on opposite sides of module board 91 is viewed from the positive z-axis. On the other hand, (b) of FIG. 4A is a perspective view of a layout of circuit elements when principal surface 91 b is viewed from the positive z-axis. FIG. 4A illustrates output transformer 15 disposed inside of module board 91 with dashed lines.

Radio frequency module 1D according to Example 2 shows a specific arrangement of circuit elements included in radio frequency module 1 according to the embodiment.

Radio frequency module 1D according to this example is different from radio frequency module 1A according to Example 1, only in the arrangement of the circuit elements included in radio frequency module 1D. The following description of radio frequency module 1D according to this example focuses on differences from radio frequency module 1A according to Example 1 while a description of the same points is omitted.

Module board 91 is a board which includes principal surface 91 a (a first principal surface) and principal surface 91 b (a second principal surface) on opposite sides of module board 91, and on which the transmission circuits and the reception circuits described above are mounted. As module board 91, for example, one of an LTCC board, an HTCC board, a component-embedded board, a board that includes an RDL, and a printed circuit board each having a stacked structure of a plurality of dielectric layers is used.

As illustrated in FIGS. 4A and 4B, in radio frequency module 1D according to this example, differential amplifier circuit 10A, PA control circuit 80, duplexers 30 and 40, matching circuits 61, 62, and 63, and switch 53 are mounted on principal surface 91 a (the first principal surface) of module board 91. On the other hand, low noise amplifier 20, switches 51 and 52, and diplexer 35 are mounted on principal surface 91 b (the second principal surface) of module board 91. Output transformer 15 is disposed inside of module board 91.

In this example, amplifying elements 12 and 13 are mounted on principal surface 91 a (the first principal surface). PA control circuit 80 is also mounted on principal surface 91 a (the first principal surface). Further, low noise amplifier 20 is a first circuit component, and is mounted on principal surface 91 b (the second principal surface).

Note that duplexers 30 and 40, switch 53, and matching circuits 61, 62, and 63 are mounted on principal surface 91 a (the first principal surface), but may be mounted on principal surface 91 b (the second principal surface). Switches 51 and 52 and diplexer 35 are mounted on principal surface 91 b (the second principal surface), but may be mounted on principal surface 91 a (the first principal surface).

Power amplifier 10 includes at least amplifying elements 12 and 13, interstage transformer 14, and output transformer 15, and thus includes many circuit elements, which leads to an increase in a mounting area. Consequently, the size of the radio frequency module is likely to increase.

To address this, the above configuration of radio frequency module 1D according to this example allows PA control circuit 80 that controls power amplifier 10 and low noise amplifier 20 to be mounted on the two sides, and thus radio frequency module 1 can be miniaturized. Low noise amplifier 20 and PA control circuit 80 that greatly affects reception sensitivity of the reception circuits are disposed with module board 91 being located therebetween, and thus deterioration of reception sensitivity caused by digital noise can be reduced.

Differential amplifier circuit 10A and low noise amplifier 20 are disposed with module board 91 being located therebetween, and thus high-level isolation between transmission and reception can be ensured.

Note that desirably, module board 91 has a multilayer structure in which a plurality of dielectric layers are stacked, and a ground electrode pattern is formed on at least one of the dielectric layers. Accordingly, the electromagnetic field shielding function of module board 91 improves.

In radio frequency module 1D according to this example, external-connection terminals 150 are disposed on principal surface 91 b (the second principal surface) of module board 91. Radio frequency module 1D exchanges electrical signals with a motherboard disposed on the negative z-axis side of radio frequency module 1D, via external-connection terminals 150. Potential of some of external-connection terminals 150 are set to the ground potential of the motherboard. On principal surface 91 b facing the motherboard out of principal surfaces 91 a and 91 b, differential amplifier circuit 10A whose height is not readily decreased is not disposed, and low noise amplifier 20 whose height is readily decreased is disposed, and thus the height of radio frequency module 1D as a whole can be decreased. Further, external-connection terminals 150 used as ground electrodes are disposed around low noise amplifier 20 that greatly affects reception sensitivity of the reception circuits, and thus deterioration of reception sensitivity of the reception circuits can be reduced.

Radio frequency module 1D according to this example further includes heat-dissipating via conductor 95V connected to a ground electrode of differential amplifier circuit 10A on principal surface 91 a, and extending from principal surface 91 a to principal surface 91 b, as illustrated in FIG. 4B. Heat-dissipating via conductor 95V is connected, on principal surface 91 b, to external-connection terminals 150 having the ground potential out of external-connection terminals 150.

According to this configuration, when differential amplifier circuit 10A is mounted on principal surface 91 a, differential amplifier circuit 10A and external-connection terminals 150 can be connected through heat-dissipating via conductor 95V. Accordingly, as heat dissipation paths for differential amplifier circuit 10A, a heat dissipation path extending along only a planar line pattern in the xy plane direction and having high heat resistance can be excluded from lines on and in module board 91. Thus, miniaturized radio frequency module 1D having improved heat dissipation from differential amplifier circuit 10A to the motherboard can be provided.

As illustrated in FIG. 3B, in a plan view of module board 91, desirably, no circuit component other than external-connection terminals 150 having the ground potential is disposed in a region included in principal surface 91 b and overlapping a region in which differential amplifier circuit 10A is disposed.

According to this configuration, no circuit component is disposed on a heat dissipation path for differential amplifier circuit 10A, and thus deterioration in characteristics of circuit components included in radio frequency module 1D due to heat generated by differential amplifier circuit 10A can be reduced.

Note that in radio frequency module 1D according to this example, low noise amplifier 20 and switches 51 and 52 may be included in single semiconductor IC 70. Accordingly, radio frequency module 1D can be miniaturized.

In radio frequency module 1D according to this example, output transformer 15 is disposed inside of module board 91, but may be disposed on principal surface 91 a or 91 b as a chip circuit component.

In radio frequency module 1D according to this example, external-connection terminals 150 may be disposed on principal surface 91 a.

[4. Advantageous Effects]

As described above, radio frequency module 1 according to the present embodiment includes: module board 91 that includes principal surfaces 91 a and 91 b on opposite sides of module board 91; power amplifier 10; a first circuit component; and PA control circuit 80 configured to control power amplifier 10. Power amplifier 10 includes: amplifying elements 12 and 13; and output transformer 15 that includes primary coil 15 a and secondary coil 15 b. One end of primary coil 15 a is connected to an output terminal of amplifying element 12. Another end of primary coil 15 a is connected to an output terminal of amplifying element 13. An end of secondary coil 15 b is connected to an output terminal of power amplifier 10. PA control circuit 80 is disposed on one of principal surfaces 91 a and 91 b. The first circuit component or amplifying elements 12 and 13 are disposed on a remaining one of principal surfaces 91 a and 91 b.

Accordingly, differential amplifying circuit 10A or the first circuit component and PA control circuit 80 are mounted on the two sides, and thus radio frequency module 1 can be miniaturized. When PA control circuit 80 and differential amplifying circuit 10A are disposed on different principal surfaces, differential amplifying circuit 10A can be prevented from receiving digital noise. Accordingly, deterioration of the quality of a radio frequency signal output from power amplifier 10 can be reduced. If PA control circuit 80 and the first circuit component are disposed on different principal surfaces, characteristics of the first circuit component can be prevented from deteriorating due to digital noise. Accordingly, small radio frequency module 1 in which deterioration of the quality of a radio frequency signal output from difference amplifying type power amplifier 10 can be provided.

In radio frequency module 1A according to Example 1, amplifying elements 12 and 13 may be disposed on principal surface 91 a.

According to this configuration, differential amplifying circuit 10A and PA control circuit 80 are disposed with module board 91 being located therebetween, and thus differential amplifying circuit 10A can be prevented from receiving digital noise.

Radio frequency module 1A according to Example 1 may further include a plurality of external-connection terminals 150 disposed on principal surface 91 b. The first circuit component is low noise amplifier 20 disposed on principal surface 91 b. Out of external-connection terminals 150, external-connection terminal 150 having a ground potential may be physically disposed between PA control circuit 80 and low noise amplifier 20 in a plan view of module board 91.

According to this configuration, on principal surface 91 b facing a motherboard, differential amplifying circuit 10A whose height is not readily decreased is not disposed, and low noise amplifier 20 whose height is readily decreased is disposed, and thus the height of radio frequency module 1A can be decreased. Further, external-connection terminals 150 used as ground electrodes are disposed between low noise amplifier 20 and PA control circuit 80 that greatly affect reception sensitivity of the reception circuits, and thus deterioration of reception sensitivity can be reduced.

Radio frequency module 1A according to Example 1 may further include an inductor connected to an input terminal of low noise amplifier 20, the inductor being disposed on principal surface 91 a.

Accordingly, the inductor and PA control circuit 80 that greatly affect reception sensitivity of the reception circuits are disposed with module board 91 being located therebetween, and thus a control line of PA control circuit 80 and the inductor can be prevented from being coupled via an electromagnetic field. Consequently, deterioration of reception sensitivity caused by digital noise can be reduced.

Radio frequency module 1A according to Example 1 may further include heat-dissipating via conductor 95V connected to a ground electrode of differential amplifying circuit 10A, heat-dissipating via conductor 95V extending from principal surface 91 a to principal surface 91 b. Heat-dissipating via conductor 95V may be connected, on principal surface 91 b, to external-connection terminal 150 having the ground potential out of external-connection terminals 150.

Accordingly, as heat dissipation paths for differential amplifier circuit 10A, a heat dissipation path extending along only a planar line pattern in the xy plane direction and having high heat resistance can be excluded from lines on and in module board 91. Thus, miniaturized radio frequency module 1A having improved heat dissipation from differential amplifier circuit 10A to the motherboard can be provided.

In radio frequency module 1D according to Example 2, the first circuit component is low noise amplifier 20 disposed on principal surface 91 b.

Accordingly, low noise amplifier 20 and PA control circuit 80 that greatly affect reception sensitivity of the reception circuits are disposed with module board 91 being located therebetween, and thus deterioration of reception sensitivity caused by digital noise can be reduced.

Radio frequency module 1D according to Example 2 may further include a plurality of external-connection terminals 150 disposed on principal surface 91 b. Amplifying elements 12 and 13 may be disposed on principal surface 91 a.

Accordingly, differential amplifying circuit 10A and low noise amplifier 20 are disposed with module board 91 being located therebetween, and thus high-level isolation between transmission and reception can be ensured.

Radio frequency module 1D according to Example 2 may further include heat-dissipating via conductor 95V connected to a ground electrode of differential amplifying circuit 10A, heat-dissipating via conductor 95V extending from principal surface 91 a to principal surface 91 b. Heat-dissipating via conductor 95V may be connected, on principal surface 91 b, to external-connection terminal 150 having a ground potential out of external-connection terminals 150.

Accordingly, miniaturized radio frequency module 1D having improved heat dissipation from differential amplifier circuit 10A to the motherboard can be provided.

In radio frequency module 1D according to Example 2, in a plan view of module board 91, no circuit component other than external-connection terminal 150 having the ground potential is desirably disposed in a region in principal surface 91 b, the region overlapping a region in which amplifying elements 12 and 13 are disposed.

According to this configuration, no circuit component is disposed on a heat dissipation path for differential amplifier circuit 10A, and thus deterioration in characteristics of circuit components included in radio frequency module 1D due to heat generated by differential amplifier circuit 10A can be reduced.

Communication device 5 includes: antenna 2; RFIC 3 configured to process radio frequency signals transmitted and received by antenna 2; and radio frequency module 1 configured to transfer the radio frequency signals between antenna 2 and RFIC 3.

Accordingly, small communication device 5 in which deterioration of the quality of a radio frequency signal output from difference amplifying type power amplifier 10 can be provided.

Other Embodiments Etc

The above has described the radio frequency module and the communication device according to the embodiment of the present disclosure, based on an embodiment, examples, and variations, yet the radio frequency module and the communication device according to the present disclosure are not limited to the above embodiment, examples, and variations. The present disclosure also encompasses another embodiment achieved by combining arbitrary elements in the embodiment, the examples, and the variations, variations as a result of applying various modifications that may be conceived by those skilled in the art to the embodiment, the examples, and the variations without departing from the scope of the present disclosure, and various apparatuses that include the radio frequency modules and the communication devices.

For example, in the radio frequency modules and the communication devices according to the embodiment, the examples, and the variations, another circuit element and another line, for instance, may be disposed between circuit elements and paths connecting signal paths, which are illustrated in the drawings.

Although only some exemplary embodiments of the present disclosure have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of the present disclosure. Accordingly, all such modifications are intended to be included within the scope of the present disclosure.

INDUSTRIAL APPLICABILITY

The present disclosure can be widely used in communication apparatuses such as mobile phones, as a radio frequency module disposed in a front-end portion that supports multiband technology. 

The invention claimed is:
 1. A radio frequency module, comprising: a module board that includes a first principal surface and a second principal surface on opposite sides of the module board; a power amplifier configured to amplify a transmission signal; a first circuit component; and a control circuit configured to control the power amplifier, wherein the power amplifier includes: a first amplifying element; a second amplifying element; and an output transformer that includes a first coil and a second coil, an end of the first coil is connected to an output terminal of the first amplifying element, another end of the first coil is connected to an output terminal of the second amplifying element, an end of the second coil is connected to an output terminal of the power amplifier, the control circuit is disposed on the first principal surface, and the first circuit component or both the first amplifying element and the second amplifying element are disposed on the second principal surface.
 2. The radio frequency module according to claim 1, wherein the first amplifying element and the second amplifying element are disposed on the second principal surface.
 3. The radio frequency module according to claim 2, further comprising: a plurality of external-connection terminals disposed on the first principal surface, wherein the first circuit component is a low noise amplifier disposed on the first principal surface, the low noise amplifier being configured to amplify a reception signal, and out of the plurality of external-connection terminals, an external-connection terminal having a ground potential is physically disposed between the control circuit and the low noise amplifier in a plan view of the module board.
 4. The radio frequency module according to claim 3, further comprising: an inductor connected to an input terminal of the low noise amplifier, the inductor being disposed on the second principal surface.
 5. The radio frequency module according to claim 3, further comprising: a heat-dissipating via-conductor connected to a ground electrode of the first amplifying element or the second amplifying element, the heat-dissipating via-conductor extending from the second principal surface to the first principal surface, wherein the heat-dissipating via-conductor is connected, on the first principal surface, to the external-connection terminal having the ground potential out of the plurality of external-connection terminals.
 6. The radio frequency module according to claim 1, wherein the first circuit component is a low noise amplifier disposed on the second principal surface, the low noise amplifier being configured to amplify a reception signal.
 7. The radio frequency module according to claim 6, further comprising: a plurality of external-connection terminals disposed on the second principal surface, wherein the first amplifying element and the second amplifying element are disposed on the first principal surface.
 8. The radio frequency module according to claim 7, further comprising: a heat-dissipating via-conductor connected to a ground electrode of the first amplifying element or the second amplifying element, the heat-dissipating via-conductor extending from the first principal surface to the second principal surface, wherein the heat-dissipating via-conductor is connected, on the second principal surface, to an external-connection terminal having a ground potential out of the plurality of external-connection terminals.
 9. The radio frequency module according to claim 8, wherein in a plan view of the module board, no circuit component other than the external-connection terminal having the ground potential is disposed in a region in the second principal surface, the region overlapping the first amplifying element and the second amplifying element.
 10. A communication device, comprising: an antenna; a radio frequency (RF) signal processing circuit configured to process radio frequency signals transmitted and received by the antenna; and a radio frequency module configured to transfer the radio frequency signals between the antenna and the RF signal processing circuit, the radio frequency module including a module board that includes a first principal surface and a second principal surface on opposite sides of the module board, a power amplifier configured to amplify a transmission signal, a first circuit component, and a control circuit configured to control the power amplifier, wherein the power amplifier includes a first amplifying element, a second amplifying element, and an output transformer that includes a first coil and a second coil, an end of the first coil is connected to an output terminal of the first amplifying element, another end of the first coil is connected to an output terminal of the second amplifying element, an end of the second coil is connected to an output terminal of the power amplifier, the control circuit is disposed on the first principal surface, and the first circuit component or both the first amplifying element and the second amplifying element are disposed on the second principal surface.
 11. The communication device according to claim 10, wherein the first amplifying element and the second amplifying element are disposed on the second principal surface.
 12. The communication device according to claim 11, wherein the radio frequency module further comprising: a plurality of external-connection terminals disposed on the first principal surface, wherein the first circuit component is a low noise amplifier disposed on the first principal surface, the low noise amplifier being configured to amplify a reception signal, and out of the plurality of external-connection terminals, an external-connection terminal having a ground potential is physically disposed between the control circuit and the low noise amplifier in a plan view of the module board.
 13. The communication device according to claim 12, wherein the radio frequency module further comprising: an inductor connected to an input terminal of the low noise amplifier, the inductor being disposed on the second principal surface.
 14. The communication device according to claim 12, wherein the radio frequency module further comprising: a heat-dissipating via-conductor connected to a ground electrode of the first amplifying element or the second amplifying element, the heat-dissipating via-conductor extending from the second principal surface to the first principal surface, wherein the heat-dissipating via-conductor is connected, on the first principal surface, to the external-connection terminal having the ground potential out of the plurality of external-connection terminals.
 15. The communication device according to claim 10, wherein the first circuit component is a low noise amplifier disposed on the second principal surface, the low noise amplifier being configured to amplify a reception signal.
 16. The communication device according to claim 15, wherein the radio frequency module further comprising: a plurality of external-connection terminals disposed on the second principal surface, wherein the first amplifying element and the second amplifying element are disposed on the first principal surface.
 17. The communication device according to claim 16, wherein the radio frequency module further comprising: a heat-dissipating via-conductor connected to a ground electrode of the first amplifying element or the second amplifying element, the heat-dissipating via-conductor extending from the first principal surface to the second principal surface, wherein the heat-dissipating via-conductor is connected, on the second principal surface, to an external-connection terminal having a ground potential out of the plurality of external-connection terminals.
 18. The communication device according to claim 17, wherein in a plan view of the module board, no circuit component other than the external-connection terminal having the ground potential is disposed in a region in the second principal surface, the region overlapping the first amplifying element and the second amplifying element. 